1. Field of the Invention
The present invention relates to a toothbrush whose brush head is designed in such a way as to be more densely equipped with bristles compared to usual toothbrushes.
2. Description of Background Art
According to the present opinion of dental science, it is desirable to use toothbrushes having a bristle field equipped as densely as possible with bristles.
In case of these so-called "multi-tuft toothbrushes", the placement of the bristles and their fixation in the brush head normally is effected by holes which were drilled into the surface of the brush head or round holes which were injected during injection molding of the brush handle.
Conventionally only the fixation of a very limited number of bristle bundles is possible, since, due to technical reasons, a minimum distance must be kept between the plurality of single holes.
Swiss Pat. No. 623,279 already discloses the design of the holes of the brush head not as round but as angular holes, especially square or rectangular holes.
It is stated that this design should render it possible to increase the quantity of bristle bundles fixed in the brush head. However, effect of increasing the quantity of bristle bundles does not occur in reality. With a well-known "multi-tuft toothbrush" having normal round bristle holes being in public use, the proportion of the hole area to the surface area of the brush head is approx. 34%, and only a proportion of 25% of the hole area may be achieved by using the square shaped the surface area bristle holes according to the preferred embodiment of Swiss Pat. No. 623,279.
So the technical solution suggested according to the Swiss Patent does not lead to any advance.